Control of Schistosoma mansoni and intestinal helminths: 8-year follow-up of an urban school programme in Bujumbura, Burundi.

Annual selective chemotherapy with praziquantel was implemented in primary schools in the endemic suburbs of Bujumbura from 1984 to 1992. During the first 6-year period, the overall prevalence among pupils decreased from 23.3% to 9.1%, a reduction of 61%. During the following 2-year period, in which only children from the 1st, 4th and 6th grade were examined in two of the four endemic suburbs (maintenance strategy), the prevalence decreased further to 6.4% or a 73% reduction from the beginning of the programme. The impact of annually repeated selective chemotherapy was more important on the intensity than on the prevalence of infection. It was also more pronounced in the senior grades of primary school. Its cumulative effect tended to decline over the years. The prevalence of infection in new entrants to the programme also decreased over the years, indicating a reduction of transmission. This change in transmission was different in each suburb and related to changes in the sanitary situation, the degree of urbanization and the accessibility to rural transmission sites. The results of helminth control, a secondary aspect of the school programme, were proportionately less pronounced than those obtained for schistosomiasis. The improvement in hygienic conditions has also contributed much to the outcome of this latter type of control. The cost, per person protected, of the programme was comparable with what has been reported by other, similar programmes. Application of a maintenance strategy to 57% of the target population has reduced the cost by 40%.